Methods, systems, apparatus and rotor for applying granular material
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to methods, systems, apparatus and a rotor for metering, conveying and dispensing granular materials and/or liquids and, in particular, to methods, systems, apparatus and a rotor for metering, conveying and dispensing granular materials onto a plurality of zones and/or liquids onto a plurality of regions. 
     2. Description of Related Art. 
     Various forms of devices for applying particulate or liquid pesticides or the like are known. These can comprise structures for mounting on a motorized vehicle or a pull-type vehicle. 
     U.S. Pat. No. 4,630,773 discloses a device for spreading granular fertilizer, liquid herbicide and liquid insecticide. The device is on a motorized vehicle and has a plurality of product bins and liquid tanks. Feeder devices meter granular products from the bins under computer control onto a conveyor through a single rotary spreader onto an area of the ground. Such devices spread material on a relatively narrow strip of ground generally requiring multiple passes by the vehicle. 
     U.S. Pat. No. 4,569,486 discloses a pneumatic device for distributing particulate material such as fertilizer, herbicide or seeds on a pull-type vehicle with booms which extend to one or the other side of the vehicle. Such devices are useful on open territory such as farmland. However, the vehicle cannot pass near obstructions like signs, poles or trees without altering the position of the booms requiring either a change in vehicle path to avoid the obstructions or time and effort to change the position of the booms. 
     Such devices are designed to apply numerous products, such as seeds, fertilizers, pesticides including herbicides, insecticides and fungicides, and other agricultural chemicals. The product per unit area dispensing rate varies greatly depending on the product being applied. The pesticides typically applied in the past have active ingredient concentrations of about 15% or less by weight. This requires such pesticides to be applied at high product per unit area rates, such as greater than 10 pounds per acre (11.2 Kg/ha) and more typically 20 to 30 pounds per acre (22.4 to 33.6 Kg/ha). Other products, such as fertilizers, often require application rates of several hundred pounds per acre. Since previous product application rates are so high, the dispensing devices have not needed to be able to accurately meter and uniformly apply small quantities of dry granular material. 
     There are granular materials available having about 60% to about 80% concentration by weight of active ingredients. Some of these materials need only be applied at rates of a fraction of an ounce per acre to about one pound per acre, such as Oust®, Escort® and Telar®, all commercially available from E. I. du Pont de Nemours and Company with offices in Wilmington, Delaware. Other of these materials need only be applied at about one pound per acre (1.1 Kg/ha) to about 10 pounds per acre (11.2 Kg/ha), such as Karmex® and Krovar®, both also available from E. I. du Pont de Nemours and Company. See U.S. Pat. Nos. 4,127,405, 4,383,113, 4,394,506, 4,481,029, and 4,420,325 for a further description of sulfonylurea herbicides which are granular materials that can be applied at application rates less than about 10 pounds per acre (11.2 Kg/ha). 
     In the past, products, such as pesticides, were frequently applied to the ground with liquid, such as water, for many reasons. Dry granular materials are frequently pulsed through metering devices resulting in an uneven application of the product on the ground. Dry granular materials are easily broken up in systems causing the product to be more easily blown away by the wind once released from the dispensing system. Existing devices can not apply product far, i.e., greater than about 10 or 20 feet, from a point of release on a dispensing vehicle without spraying the product in a liquid form. However, carrying the liquid reduces space for the actual product and, thus, increases application costs. 
     In view of the high concentrate granular materials available today and the cost savings associated with applying a product in granular form, it is desirable to provide a system for applying products in the form of dry granular material(s) at low application rates including less than 10 pounds per acre (11.2 Kg/ha) to as low as about one ounce per acre (1.1 Kg/ha). 
     Unique needs exist in applying pesticides near railroad tracks. For instance, different pesticides may best be applied on different zones or regions that vary with distance from the centerline between the railroad tracks. It is also desirable to have the ability to apply different rates of the same or different product(s) to different zones along the tracks. At certain locations along tracks, such as near intersections with roads, it is desirable to apply pesticides on wider strips of land from the tracks than other track locations. Obstructions, such as signs, trees, fences and poles, are common along railroad tracks making the use of extended booms impractical. 
     Therefore, it is desirable to provide a boomless system for applying products in the form of dry granular materials, especially along railroad tracks, where different products can be applied at different rates on different zones substantially without pulsing or attrition of the material. 
     However, some products may only be available in liquid form or, for some reason, it may be preferred to apply a product in liquid form. Therefore, it is desirable to provide a system for applying at least one dry granular material at rates less than about 10 pounds per acre (11.2 Kg/ha) to about one ounce per acre (1.1 Kg/ha) without pulsing or attrition of the material onto a plurality of zones and/or at least one liquid onto a plurality of regions. 
     SUMMARY OF THE INVENTION 
     This invention relates to a metering rotor for use in metering granular material comprising: 
     a rotor having an axis of rotation and an outer circumferential surface having indentations arranged in the surface in circumferential rows with each of the rows offset with respect to adjacent rows such that any radial plane including the axis contains a substantially constant cross section of the indentations. 
     This invention further relates to an apparatus for metering granular material substantially without pulsing and attrition comprising: 
     a rotor having an axis of rotation and an outer circumferential surface having indentations arranged in the surface in circumferential rows with each of the rows offset with respect to adjacent rows such that any radial plane including the axis contains a substantially constant cross section of the indentations; 
     a housing for partially enclosing and supporting the rotor, the housing having a first and a second opening, each of the openings providing access to the rotor surface, the openings spaced from one another; 
     a gate having a cylindrical surface positionable between the housing and the rotor to selectively control the size of the first housing opening; and 
     a blocking mechanism positioned adjacent the rotor cylindrical surface to prevent excess material from entering the first housing opening, 
     whereby when the material is fed by gravity to the first housing opening, the rotor is rotated with respect to the gate and the housing, and the gate is positioned to open the first housing opening, then the material is metered through the apparatus and out the second housing opening. 
     This invention further relates to a system for applying at least one granular material substantially uniformly, substantially without pulsing or attrition, onto a plurality of substantially different zones, comprising: 
     a hopper having a plurality of compartments, each of the compartments having an inlet and outlets, the hopper for receiving at least one of the granular materials in each of the compartments; 
     means for metering the granular material(s) connected to each of the outlets; 
     a collection trough having a plurality of sections, each of the sections having an outlet and positioned to receive the granular material(s) from at least one of the metering means; and 
     means for conveying and dispensing the material(s) from each of the outlets of the collection trough onto one of the substantially different zones, 
     such that the material(s) are applied substantially uniformly to the zones substantially without pulsing and attrition. 
     This invention further relates to a system for applying at least one granular material substantially uniformly, substantially without pulsing or attrition, onto a plurality of substantially different zones and/or at least one liquid onto a plurality of substantially different regions, comprising: 
     means for storing the liquid(s); 
     means connected to the storing means for conveying and dispensing the liquid(s) onto the plurality of substantially different regions; 
     a hopper having a plurality of compartments, each of the compartments having an inlet and outlets, the hopper for receiving at least one of the granular materials in each of the compartments; 
     means for metering the granular material(s) connected to each of the outlets; 
     a collection trough having a plurality of sections, each of the sections having an outlet and positioned to receive the granular material(s) from at least one of the metering means; and 
     means for conveying and dispensing the material(s) from each of the outlets of the collection trough onto one of the substantially different zones, 
     such that the material(s) are applied substantially uniformly to the zones substantially without pulsing and attrition. 
     The invention is further directed to a method of applying at least one granular material onto a plurality of substantially different zones, comprising the steps of: 
     metering the material(s) from outlets of compartments of a hopper to sections of a collection trough; and 
     conveying and dispensing the materials from outlets of the collection trough through points of release onto the plurality of substantially different zones, 
     such that the material(s) are applied substantially uniformly to the zones substantially without pulsing or attrition. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention can be more fully understood from the following detailed description thereof in connection with accompanying drawings which form a part of this application and in which: 
     FIG. 1 is a schematic perspective view of a system for applying at least one granular material substantially without pulsing or attrition onto a plurality of substantially different zones and/or at least one liquid onto a plurality of substantially different regions in accordance with the present invention. 
     FIG. 2 is a schematic representation of the rear of the applying system illustrating the plurality of substantially different zones and the general location of nozzles on the system that dispense granular material on the plurality of zones. 
     FIG. 3 is a schematic illustration showing the material flow in the system from a hopper through the nozzles for zones 4 through 10. 
     FIG. 4 is a schematic illustration showing the material flow in the system from the hopper through the nozzles for zones 1, 2, 12 and 13. 
     FIG. 5 is a schematic illustration showing a side view of the material flow in the system from the hopper through the nozzles for zones 3 and 11. 
     FIG. 6 is a schematic representation of a top view of the system hopper showing that it has a plurality of compartments and that each compartment has at least one outlet. 
     FIG. 7 is a side view of a nozzle that can be used for dispensing granular material onto zones 1, 2, 3, 11, 12, and 13. 
     FIG. 8 is a schematic representation of a first part of the applying system&#39;s pneumatic system. 
     FIG. 9 is a schematic representation of a second part of the conveying and dispensing system&#39;s pneumatic system. 
     FIG. 10 is a schematic representation of the applying system&#39;s hydraulic system. 
     FIG. 11 is a schematic representation of the applying system&#39;s liquid herbicide conveying and dispensing system. 
     FIG. 12 is a top plan view of a metering device in accordance with the present invention. 
     FIG. 13 is a front side elevation of the metering device of FIG. 12. 
     FIG. 14 is a back side elevation of the metering device of FIG. 12. 
     FIG. 15 is an enlarged sectional view taken on the line 15--15 of FIG. 12 showing the relationship of parts of the metering device including a rotor, a housing, a gate and wiping mechanisms. 
     FIG. 16 is a view like FIG. 15 showing a metering device of the present invention having a smaller rotor. 
     FIG. 17 is a sectional view taken on the line 17--17 of FIG. 13 which shows drive connections of the gate and the rotor. 
     FIG. 18 is an electrical block diagram for the conveying and dispensing system. 
     FIG. 19 is another electrical block diagram of the main control module and operator controls of FIG. 18. 
     FIG. 20 illustrates detailed preferred embodiments of gate motor control circuits, flow sensor circuits, rotor motor control circuits, and liquid herbicide solenoid circuits of FIG. 19. 
     FIG. 21 illustrates a detailed preferred embodiment of the operator controls. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
     Throughout the following detailed description, similar reference numerals refer to similar elements in all Figures of the drawings. 
     Referring to FIG. 1, there is illustrated a schematic perspective view of a system 20 for applying at least one granular material at low application rates including less than 10 pounds per acre (11.2 Kg/ha) to as low as about one ounce per acre (70 gr/ha) substantially without pulsing or attrition onto a plurality of substantially different zones and/or at least one liquid onto a plurality of substantially different regions in accordance with the present invention. 
     The applying system 20 includes a hopper 22 for receiving the granular materials, means for metering 24 the granular materials from the hopper 22, a collection trough 26 for receiving the materials from the metering means 24, means for conveying and dispensing 28 the materials from the trough 26, means for storing 30 the liquid(s), and means for conveying and dispensing 32 the liquid(s) from the storing means 30. The system 20 is preferably supported on a vehicle 34, such as a truck, having extendible railroad wheel assemblies 36 for traveling on railroad tracks 38. 
     In a preferred embodiment, the hopper 22 has a plurality of compartments designated A1, A2, A3, B1, B2, B3, C1, C2, C3, D1, D2, and D3 in FIG. 1. Each of the compartments are adapted to receive and hold at least one granular material. All of the compartments may hold the same material(s). Alternatively, different compartments may hold different material(s). 
     Referring to FIG. 2, there is shown a schematic representation of the rear of the vehicle 34 supporting the applying system 20 illustrating the plurality of substantially different zones designated in 20 the Figure by the numbers 1-13 and the general location of nozzles N 1  -N 13  on the system that dispense granular material on the plurality of zones 1-13. When the vehicle 34 travels in a straight path, the zones are strips on the ground that are generally parallel and substantially adjacent to one another. 
     There can be any number of zones and there is at least one nozzle positioned on the vehicle 34 to spray granular material on each of the zones. In a preferred embodiment shown in FIG. 2, there are 13 zones and one nozzle for each zone. The zones 1-13 are symmetric about a point on the ground corresponding to the center of the vehicle 34. The nozzle N 1  is positioned to spray granular material onto the zone 1. The nozzle N 2  is positioned to spray granular material onto the zone 2. The nozzle N 3  is positioned to spray granular material onto the zone 3. The nozzle N 4  is positioned to spray granular material onto the zone 4. The nozzle N 5  is positioned to spray granular material onto the zone 5. The nozzle N 6  is positioned to spray granular material onto the zone 6. The nozzle N 7  is positioned to spray granular material onto the zone 7. The nozzle N 8  is positioned to spray granular material onto the zone 8. The nozzle N 9  is positioned to spray granular material onto the zone 9. The nozzle N 10  is positioned to spray granular material onto the zone 10. The nozzle N 11  is positioned to spray granular material onto the zone 11. The nozzle N 12  is positioned to spray granular material onto the zone 12. The nozzle N 13  is positioned to spray granular material onto the zone 13. 
     In the embodiment illustrated in FIG. 2, from left to right zone 1 is about 14 feet (4.27 meters) wide, zone 2 is about 14 feet (4.27 meters) wide, zone 3 is about 10 feet (3.05 meters) wide, zone 4 is about 4 feet (1.22 meters) wide, zone 5 is about 3 feet (0.91 meters) wide, zone 6 is about 3 feet (0.91 meters) wide, zone 7 is about 4 feet (1.22 meters) wide, zone 8 is about 3 feet (0.91 meters) wide, zone 9 is about 3 feet (0.91 meters) wide, zone 10 is about 4 feet (1.22 meters) wide, zone 11 is about 10 feet (3.05 meters) wide, zone 12 is about 14 feet (4.27 meters) wide, and zone 13 is about 14 feet (4.27 meters) wide. Thus, nozzles N 4  -N 10  spray material on a 24 foot (7.32 meter) wide path and all the nozzles cover a 100 foot (30.48 meter) wide path. 
     FIG. 3 is a schematic illustration showing the material flow in a preferred embodiment of the system 20 from the compartments A3, B3, C3 and D3 of the hopper 22 through the nozzles N 4  through N 10  for spraying onto zones 4 through 10, respectively. Each of the compartments of the hopper 22 has an inlet and at least one outlet 40 positioned at substantially the bottom of the compartment. A metering device or means for metering 24 is connected to each of the hopper outlets 40. A material flow sensor 42 is positioned beneath each metering device 24 to sense the flow of material exiting from the metering device 24 and to provide an electrical signal representative of the sensed flow. Any material flow sensor may be used as long as it serves these functions. 
     One material flow sensor that has been found satisfactory is described as follows. The flow sensor may comprise a piezoelectric device (such as Panosonic omnidirectional electret condenser microphone part number p9932 available from Digi-Key Corp., with offices in Thief River Falls, Minnesota) to detect the impact of granules as they fall through material delivery tubes 44. The microphone can be installed to slightly protrude into the tube 44 at an angle of about 30° from vertical. It is connected to a control circuit which monitors the number of impacts per unit time and sends a &#34;flow&#34; or &#34;no flow&#34; signal to a main control module 270. 
     Hoses, tubes or conduits 44 can be used to direct the fall of the granular material from the sensors 42 to a section of the collection trough 26. Each of the sections of the collection trough 26 is positioned to receive the granular material(s) from at least one of the metering means 24. It has been found that the material falling from the hoses 44 sufficiently mixes itself due to the dispersion from the hoses 44. However, a mixing device can be adapted to mix the material in each section of the collection trough 26. Each section of the collection trough 26 has at least one outlet at or near its bottom. An airmover 48 is connected to each of the outlets 46 of the trough 26 to receive the mixed material falling out of the trough outlets 46. The term &#34;airmover&#34; as used herein is intended to include any means for pneumatically moving the material. An illustrative airmover that can be used in the present system is commercially available under model number AM750D from Nortel Machinery, Inc., located at Buffalo, New York. One end of a hose or conduit 50 is connected to each of the airmovers 48 to direct the material to and then through one of the nozzles, e.g., nozzle N 4 , which is connected to the other end of the hose 50. Any nozzle can be used for the nozzles N 4  -N 10  as long as it provides relatively uniform dispersion of the granular material over the zone being sprayed. For uniformly spraying granular material at low application rates including less than 10 pounds per acre (11.2 Kg/ha) to as low as about one ounce per acre (70 gr/ha) substantially without pulsing or attrition onto the zones 6-8 having the dimensions illustrated in FIG. 2, it has been found satisfactory to use as the nozzle Upholstery Tool model no. 68-34691 sold by Eureka with offices at Bloomington, Illinois. For uniformly spraying granular material at low application rates including less than 10 pounds per acre to as low as about one ounce per acre substantially without pulsing or attrition onto the zones 5 and 9 having the dimensions illustrated in FIG. 2, it has been found satisfactory to use as the nozzle ShopVac Car Tool model no. 90105 sold by Shop Vac with offices at Williamsport, Pennsylvania. For spraying similar material(s) at low application rates including less than 10 pounds per acre to as low as about one ounce per acre substantially without pulsing or attrition on zones 4 and 10, it has been found satisfactory to use as the nozzle Crevice Tool part no. 14-078 also sold by Eureka. Preferably, the airmover 48 generates an air stream in the range of about 50 through 70 miles (80.47 through 112.65 Km) per hour at the release point of the nozzles N 4  -N 10 . 
     If one wants to spray the same material(s) on more than one zone, then the material(s) for these zones can be supplied from the same trough section and, thus, the same hopper compartment outlet(s) 40. However, it is preferred that the collection trough 26 have as many sections as there are nozzles or zones and that each section be adapted to receive material from at least four compartments of the hopper 22 as illustrated in FIG. 3. 
     Each one of the metering devices is controllable such that it can be turned on or off by the operator and it meters granular material at a rate proportional to the speed of the vehicle 34. Thus, assuming that each one of the compartments A3, B3, C3 and D3 holds a different granular material in it, then material from any one or any combination of the compartments A3, B3, C3 and D3 can be sprayed onto each one of the zones 4 through 10 when the vehicle 34 is moving. 
     Referring to FIG. 4, there is depicted a schematic illustration showing the material flow in the system 20 from the hopper 22 through the nozzles N 1  -N 3  and N 11  -N 13  for zones 1, 2, 3, 11, 12 and 13, respectively. The material flow path in FIG. 4 is the same as in FIG. 3, except in addition to the airmover 48 providing acceleration to the material(s) an air blower 52 is connected to the respective nozzles, e.g., nozzle 1, by a hose or conduit 54 to spray the material(s) to zones farther from the vehicle 34. The term &#34;air blower&#34; is intended herein to mean any pneumatic means for providing additional acceleration to the material. FIG. 4 illustrates the material flow from the compartments A1, B1, C1 and D1. The material flow from the compartments A2, B2, C2 and D2 is the same as shown in FIG. 4, except for the distinctions illustrated in FIG. 5. 
     FIG. 5 is a schematic illustration showing a side view of the material flow in the system from the hopper 22 through the nozzles N 3  and N 11  for zones 3 and 11, respectively. For zones 3 and 11, two outlets 40 are provided from the compartments B2 and C2. Assuming identical metering devices 24 are connected to each of the outlets on the hopper 22, this enables twice as much material from the compartments B2 and C2 to be fed into the sections of the trough 26 feeding material(s) to nozzles 3 and 11. 
     Preferably, the combined air velocity generated by the airmovers 48 and the air blowers 52 cause air streams in the range of about 150 through 200 miles (241.4 through 321.9 Km) per hour at the release point from the nozzles N 1  -N 3  and N 11  -N 13 . An acceptable air blower for the present system 20 is commercially available from Paxton Blowers with offices at Santa Monica, California, under model number RM97A. 
     Referring to FIG. 6, there is a schematic representation of a top view of the system hopper 22 showing that it has a plurality of compartments A1, A2, A3, B1, B2, B3, C1, C2, C3, D1, D2, and D3 and that each compartment has at least one outlet 40. The numbers in the outlets 40 represent the zone number that can be supplied by the outlet. Each set of the outlets 40 in the compartments A3, B3, C3 and D3 with the same numbers in them, e.g., 7, can provide materials to a corresponding section of the trough 26 and then through a corresponding nozzle, e.g., N 7 , onto a corresponding one of the zones, e.g., 7, as illustrated in relation to FIG. 3. Similarly, each set of the outlets in the compartments A1, B1, C1 and D1 having the same number in them, e.g., 12, are adapted to provide materials to a section of the collection trough 26 and then through the corresponding nozzle, e.g., N 12 , onto the corresponding zone, e.g., 12, as illustrated in FIG. 4. Finally, each set of the outlets in the compartments A2, B2, C2 and D2 having the numbers 3 plus 3A or 11 plus 11A in them are adapted to provide materials to a section of the collection trough 26 and then through the corresponding nozzle, e.g., N 3  or N 11 , onto the corresponding zone, e.g., 3 or 11, as illustrated in FIGS. 4 and 5. 
     FIG. 6 further shows a preferred layout or positioning of the compartments A1, A2, A3, B1, B2, B3, C1, C2, C3, D1, D2, and D3 and the outlets 40 with respect to the vehicle 34. The compartments form a matrix of rows designated by the numbers 1, 2 and 3, and columns designated by the letters A, B, C and D. The row of the compartments A1, B1, C1 and D1 is closest to the front of the vehicle 34. Whereas, the row of the compartments A3, B3, C3 and D3 is closest to the rear of the vehicle 34. The column of the compartments A1, A2 and A3 is closest to the driver side of the vehicle 34. Adjacent to the A column is the B column. Adjacent to the B column is the C column. The D column is the closest to the passenger side of the vehicle 34. From front to back, the outlets are adapted to supply material to the following zones: 1, 13, 2, 12, 11 (two outlets are provided in compartments B2 and C2 for this purpose), 3 (two outlets are provided in compartments B2 and C2 for this purpose), 10, 4, 9, 5, 8, 6, and then 7. 
     FIG. 7 is a side view of a nozzle, e.g., N 1 , that can be used for dispensing dry granular material(s) at low application rates including less than 10 pounds per acre to as low as about one ounce per acre substantially without pulsing or attrition onto zones 1, 2, 3, 11, 12, and 13. All of the nozzles N 1  -N 13  are part of the conveying and dispensing means 28, but only the nozzles N 1 , N 2 , N 3 ,, N 11 , N 12 , and N 13  that apply material onto zones 1, 2, 3, 11, 12, and 13, respectively, include means for introducing a first air stream carrying granular material at a first speed into a second air stream at a second speed substantially without attrition of the material. More specifically, the nozzle N 1 , for instance, comprises a first tube or pipe 56 having a first inlet end 58 and a second outlet end 60 and a second tube or pipe 62 having a first inlet end 64 and a second outlet end 66. Preferably, the tubes 56 and 62 are cylindrical and the diameter of the second tube 62 is about twice the diameter of the first tube 56. The exterior of the first tube 56 is connected to an edge 68 defining a hole in the side of the second tube 62. The inlet end 60 of the first tube 56 preferably extends slightly into the interior of the second tube 62 such that there is a distance D between the inlet end 60 and the second tube 62. Furthermore, preferably the first and second tubes 56 and 62 have longitudinal axes that intersect with each other at an angle α of about 10°. The inlet end 58 of the first tube 56 is for connection to the hose 50 which is also connected to the airmover 48. The inlet end 64 of the second tube 62 is for connection to the hose 54 which is also connected to the air blower 52. See FIG. 5. 
     FIG. 8 is a schematic representation of a first part of the applying system&#39;s pneumatic system. Air is supplied through a line 70, such as, by a compressor 71 through a pressure vessel 72. A solenoid valve 74 is positioned in the line 70 to turn the air on or off. Preferably, one or more air dryers 76 is or are positioned to dry the air in the line 70. The line 70 is connected to a manifold 78 having a plurality of outlets 80, one of the outlets 80 for each section of the collection trough 26 which in a preferred embodiment is 13. More specifically, one of the manifold outlets 80 is connected by the line 70 to each of the airmovers 48. An air filter 82 and/or an air pressure regulator 84 may be positioned in the line 70. 
     FIG. 9 is a schematic representation of a second part of the applying system&#39;s pneumatic system. In a preferred embodiment, two of the air blowers 54 are used. The air blowers 54 can be chosen to be powered by the system&#39;s 20 hydraulic system. One air blower 52 is used as illustrated in FIG. 9 to supply air to the nozzles N 1 , N 2 , and N 3 . Similarly, another one of the air blowers 52 is used to supply air to the nozzles N 11 , N 12  and N 13 . More specifically, each one of the air blowers 52 is connected by a hose or conduit 54 to a splitter 86 which divides the air into three hoses 54. Each one of the hoses 54 is connected to the inlet end 64 of one of the nozzle tubes 62. 
     FIG. 10 is a schematic representation of the applying system&#39;s hydraulic system. The vehicle engine 90 provides the power for the system&#39;s 20 hydraulic system. A first power take-off mechanism 95 is connected to the transmission 92 of the vehicle engine 90. The power take-off mechanism 95 is operable such as by a lever within the cab of the vehicle 34. Such power take-off mechanisms are well known and, thus, need not be described in any further detail. The power take-off mechanism 95 is connected to and energized a first hydraulic pump 96 for circulating hydraulic fluid or liquid to operate the extendible railroad wheel assemblies 36. 
     The pump 96 supplies the fluid from a reservoir 114 through lines 100 to one or more hydraulic cylinders 102. Valves 104 operable, for instance, by manual levers 106, are positioned in the lines 100 to control supplying the fluid to one or the other end of the cylinders 102 and to return the fluid from the opposite end of the cylinders 102 to the reservoir 114. With the valves 104 positioned as illustrated in FIG. 10, the fluid enters the cylinders 102 pushing the pistons 108 to their extended positions lowering the extendible railroad wheel assemblies 36. When the valves 104 are moved by the levers 106 to their second positioned, fluid is supplied from the first pump 96 to move the pistons 108 to their contracted or non-extended positions raising the railroad wheel assemblies 36. In a preferred embodiment, one of the pistons 108 is connected by a rod 110 to a front railroad wheel assembly 36 including two railroad wheels for the front of the vehicle 34. Further, one of the pistons 108 is connected by a rod 111 to one of the vehicle rear railroad wheels and another one of the pistons 108 is connected by a rod 112 to another one of the vehicle rear railroad wheels in the rear railroad wheel assembly 36. Railroad wheel assemblies 36 are commercially available under model numbers RW1630-RU from Diversified Metal Fabricators, Inc., with offices in Atlanta, Georgia. 
     A second power take-off mechanism 94 is connected to the transmission 92 of the vehicle engine 90. The second power take-off mechanism 94 is similarly operable such as by a lever within the cab of the vehicle 34. The second power take-off mechanism 94 is connected to and energizes a second hydraulic pump 98 for circulating hydraulic fluid or liquid to energize the air blowers 52 and the liquid pesticide conveying and dispensing system. 
     The second hydraulic pump 98 supplies hydraulic fluid or liquid from one or more reservoirs 114, 116 through lines to a first hydraulic motor 120, a second hydraulic motor 122 and a third hydraulic motor 124. The first hydraulic motor 120 is connected to and energizes a hydraulic pump 126 in the liquid pesticide conveying and dispensing system. The second hydraulic motor 122 is connected to and energizes one of the air blowers 52. The third hydraulic motor 124 is connected to and energizes the other one of the air blowers 52. A solenoid valve 128 is in the line 118 which is operable to turn the first motor 120 on and off. A solenoid valve 130 is in the line 118 which is operable to turn the second and third motors 122 and 124 on and off. A pressure relief valve 131 can be located in the system for returning the fluid to the reservoir(s) 114, 116 and bypassing the first, second and third motors 120, 122, and 124. Means can be included in the hydraulic system for filtering and/or cooling, such as by a radiator 132, the fluid. 
     FIG. 11 is a schematic representation of the applying system&#39;s liquid conveying and dispensing system. Liquid is stored in the tank 30. The hydraulic pump 126 pumps the liquid from the tank 30 through a line 135 to a manifold 140. A manual on/off valve 134 and/or a filter 136 and/or a pressure regulator 138 may be in the line 135. Further, a flow meter or sensor 133 and an adjustable valve 137 are in the line and electrically connected to a flow control unit positioned in the cab of the vehicle. The flow control unit is chosen to enable the vehicle driver or passenger to control the volume of liquid flow through the valve 137 as a function of the vehicle speed. One commercially acceptable unit for this purpose is sold by Raven Industries, Inc., with offices at Sioux Falls, South Dakota under model number SCS440. The manifold 140 has a plurality of outlets, each of the outlets for providing the liquid to a different array of nozzles 176 for spraying the liquid onto the plurality of substantially different regions. One end of a line is connected to each of the outlets of the manifold 140. In a preferred embodiment, the manifold 140 has three lines 144, 146 and 148. A solenoid valve 142 is in each of the lines 144, 146 and 148 and is operable to turn liquid flow on or off in the lines 144, 146 and 148. The other end of the lines 144, 146 and 148 are connected to other manifolds 150, 152 and 154, respectively. Each of these other manifolds 150, 152 and 154 have a plurality of outlets connected to lines 174. Each of the lines 174 similarly has a solenoid valve 156 in it which is operable to turn liquid flow on or off in the respective line 174. One or more nozzle 176, e.g., 3, 5 or 6, is positioned in each of the lines 174 downstream of the solenoid valves 156. A return line 178 can be connected to the tank 30 and the line 135 between the pump 126 and the manifold 140. A pressure relief valve 180 can be in the return line 178 such that when the pressure in the manifold 140 increases to a predetermined value, such as by the closing of one or more of the solenoid valves 142 and/or 156, excess liquid passes through the valve 180 back to the tank 30. 
     Each of the arrays of nozzles 176 can be located on a different area of the vehicle 34. For instance, referring to FIG. 1, one of the arrays of the nozzles 176, such as the array supplied by the line 146, can be attached to a multi-positionable boom on the front of the vehicle 34 to spray the liquid generally on regions in front of the vehicle 34 covering the zones designated 6, 7 and 8 in FIG. 2. Another one of the liquid nozzle arrays, such as the array supplied by the line 144, can be positioned on the passenger side of the vehicle with its nozzles 176 positionable to spray the liquid generally in regions covering the zones designated 9 and 10 in FIG. 2. Another one of the liquid nozzle arrays, such as the array supplied by the line 148, can be positioned on the driver side of the vehicle with its nozzles 176 positionable to spray the liquid generally in regions covering the zones designated 4 and 5 in FIG. 2. 
     FIG. 12 is a top plan view of a metering device or apparatus 24 in accordance with the present invention. FIG. 13 is a front side elevation of the metering device 24 of FIG. 12. FIG. 14 is a back side elevation of the metering device 24 of FIG. 12. FIG. 15 is an enlarged sectional view taken on the line 15--15 of FIG. 12 showing the relationship of parts of the metering device including a rotor, a housing, a gate and wiping mechanisms. FIG. 16 is a view like FIG. 15 showing a metering device of the present invention having a smaller rotor. FIG. 17 is a sectional view taken on the line 17--17 of FIG. 13 which shows drive connections of the gate and the rotor. 
     Referring to FIGS. 12, 15 and 17, the metering device 24 includes a rotor 190, a housing 194, a gate 200 and a blocking mechanism 202, 204. 
     The rotor 190 has an axis of rotation and an outer circumferential surface 191 having indentations 192 arranged in the surface 191 in circumferential rows with each of the rows offset with respect to adjacent rows such that any radial plane including the rotor axis contains a substantially constant cross section of the indentations 192. Each of the indentations 192 has a volume in a range of about 35 through about 350 cubic millimeters. In one embodiment, the indentations 192 are cylindrical about axes that are parallel to the rotor axis. Each of the cylindrical indentations 192 is preferably configured to comprise less than half of a cylinder. Preferably, each of the cylindrical indentations 192 is defined by a plane intersecting a cylinder. Preferably, the cylinder&#39;s diameter D is about 3 or 4 times its length L. Further, the plane preferably contains a line about one quarter of the cylinder&#39;s diameter away from the cylinder&#39;s longitudinal axis and is parallel to the cylinder&#39;s longitudinal axis. Preferably, the segments formed by the intersection of the plane and the cylindrical surface of the cylinder are equally spaced from the cylinder&#39;s longitudinal axis. 
     The rotor 190 can have a central passage 206 through which extends a shaft 208 about which the rotor 190 is adapted to rotate. A rectangular block 210 can be positioned in mating grooves in the passage 206 and the shaft 208 to prevent rotation between the passage 206 and the shaft 208. Alternatively, the rotor 190 can be integral with or connected to the shaft 208 in any fashion. End portions 212 of the shaft 208 can be reduced in diameter with respect to the central portion of the shaft 208. The shaft end portions 212 can be rotatably mounted in cylindrical bushings or bearings 214. 
     The housing 194 can be mounted to the hopper 22. The housing is configured to partially enclose and rotatably support the rotor 190. The housing 194 can have a cylindrical inner surface 195 defining a space for the rotor 190. The cylindrical inner surface 195 is configured such that it is spaced with respect to the rotor outer circumferential surface 191. The housing 194 has a first opening 196 and a second opening 198. Each of the openings 196, 198 provides access to the rotor surface 191 and the openings 196, 198 are spaced from one another. Preferably, the openings 196, 198 align in a straight line through the housing 194. One end of the housing 194 is rotatably connected to one of the cylindrical bushings 214. Another end of the housing 194 rotatably supports the other cylindrical bushing 214. 
     Referring to FIGS. 12, 14 and 17, a rotor motor gear 216 is connected to one of the shaft end portions 212. A chain 218 connects the rotor motor gear 216 to a gear 221 of a rotor motor assembly 220 including a motor 222 and optionally a speed reducer gearbox 224. 
     Referring again to FIGS. 12, 15 and 17, the gate 200 has a cylindrical surface 226 selectively positionable between the housing 194 and the rotor 190 to control the size of the first housing opening 196. In other words, the gate 200 selectively controls the surface area of the rotor 190 exposed to receive material from the first housing opening 196. The surface 226 has a stepped edge 228 which is configured such that when the gate 200 is in a first fully opened position with respect to the housing 194 as illustrated in FIG. 12, granular material can enter through the first opening 196 into all of the circumferential rows of the indentations 192. FIG. 12 shows 7 such rows. When the gate 200 is in a second partially closed position with respect to the housing 194, granular material can enter through the first opening 196 into less than all, e.g., 2, of the circumferential rows of the indentations 192. Sides 230 of the gate 200 are rotatably mounted on the bushings 214. A cylindrical portion 232 extends from one of the sides of the gate 200 and is connected to a gate motor gear assembly 234 such that when a gear 236 of the gear assembly 234 rotates about the shaft 208, the gate 200 rotates about the shaft 208. The gate motor gear assembly 234 has an extension 250 which has an outer surface 252 that is cylindrical, except for one flat portion 254. 
     One of the ends of the housing 194 is connected to another bushing 242 which rotatably supports the cylindrical portion 232. A washer or spacer 238 can be positioned around the cylindrical portion 232 between the bushing 214 and the gate motor gear assembly 234. A polymer housing lining 240 can be located between the gate sides 230 and the housing 194. 
     Referring to FIGS. 12, 13 and 17, a chain 244 connects the gate motor gear 236 to a gear 245 of a gate motor assembly 246 including a motor 248 and optionally a speed reducer gearbox 250. 
     A first switch mechanism 256 and a second switch mechanism 258 are connected to the housing 194. Each of the mechanisms 256 and 258 has a pivotable arm 260 biased towards and in contact with the outer surface 252. Illustrative switch mechanisms are available from Newark Electronics with offices at Chicago, Illinois, under stock number E23-00k. Referring to FIG. 13, when the gear assembly 234 rotates clockwise, the arm 260 of the switch mechanism 256 will pivot towards the gear assembly 234 when the arm 260 of the switch mechanism 256 comes in contact with the flat portion 254. This opens a circuit stopping the gate motor assembly 246 with the gate 200 in its first fully opened position. When the gear assembly 234 rotates counter clockwise, the arm 260 of the switch mechanism 256 will pivot towards the gear assembly 234 when the arm 260 of the switch mechanism 258 comes in contact with the flat portion 254. This opens a circuit stopping the gate motor assembly 246 with the gate 200 in its second partially opened position. 
     Referring to FIGS. 15 and 17, the blocking mechanism 202, 204 preferably comprises a first wiping mechanism 202 and a second wiping mechanism 204. The first and second wiping mechanisms 202, 204 can be identical. They are connected to the housing 194 between the housing 194 and adjacent the rotor outer cylindrical surface 191 to prevent excess material from entering the first housing opening 196. They are positioned across from one another in the first housing opening 196. Each of the wiping mechanisms 202, 204 can generally lie in a radial plane containing the rotor axis of rotation. The wiping mechanisms 202, 204 can be brushes or wiper blades for brushing or wiping the rotor outer cylindrical surface 191 while the rotor 190 is rotating in the housing 194. The wiping mechanisms 202, 204 only allow granular material in the indentations 192 to pass into the opening 196 through the metering device 24 and out the second opening 198. The wiping mechanisms can be separate parts from the housing 194 as illustrated in the drawings. However, it is to be understood that the wiping mechanisms could be part of the housing 194. 
     In operation when the material is fed by gravity into the first housing opening 196, the rotor 190 is rotated with respect to the gate 200 and the housing 194, and the gate 200 is positioned to open the first housing opening 196, then the material is metered through the apparatus and out the second housing opening 198 substantially. 
     Referring to FIG. 16, there is illustrated another embodiment of the metering device 24&#39; of the present invention. The device 24&#39; is the same as the one depicted in FIG. 15, except the rotor 190&#39; has a smaller diameter, the gate 200&#39; is correspondingly smaller and the wiping mechanisms 202&#39; and 204&#39; are longer. Assuming the rotors are rotating at the same number of revolutions per minute, the metering device 24&#39; illustrated in FIG. 16 meters less granular material per unit time than the metering device 24 of FIG. 15. Thus, any number of different metering devices 24, 24&#39; can be used on the system 20 enabling different flow rates for different granular materials or different flow rates of the same material for different zones. 
     FIG. 18 is an electrical block diagram for the applying system 20. A main control module 270 is connected to receive power from a power supply 272. Operator controls 274 are located in the cab of the vehicle 34 and are connected to provide signals to the main control module 270. A speedometer cable inductance sensor 276 is connected to provide electrical signals representative of the speed of the vehicle 34 through the operator controls 274 to the main control module 270 or directly to the main control module 270. A computer 278, such as a laptop computer, and/or a printer 275 can be located in the cab of the vehicle 34 connected to the main control module 270 to interact with the main control module 270. 
     The main control module 270 can be connected by separate lines to parts of liquid pesticide solenoid circuits 277, one solenoid circuit 277 for controlling each of the solenoid valves 156, more specifically, for turning the liquid pesticide flow on and off through the nozzles 174. 
     Further, the main control module 270 is designed to control the metering devices 24, 24&#39;. This is accomplished by connecting the main control module 270 to at least one meter device control assembly 280. Preferably, one cable 279 connects the main control module 270 to a meter device control assembly 280 for o each meter device 24, 24&#39; supplying one of the zones. For instance, for the embodiment illustrated in FIG. 6, one of the cables 279 connects the main control module 270 to four meter device control assemblies 280, a first meter control assembly 280 (A1--1) for controlling the meter device 24 connected to the compartment A1 for conveying material to zone 1, a second meter control assembly 280 (B1--1) for controlling the meter device 24 connected to the compartment B1 for conveying material to zone 1, a third meter control assembly 280 (C1--1) for controlling the meter device 24 connected to the compartment C1 for conveying material to zone 1, and a fourth meter control assembly 280 (D1--1) for controlling the meter device 24 connected to the compartment D1 for conveying material to zone 1. A separate one of the cables 279 can be used to connect the main control module 270 to a meter control assembly 280 (B2-3A) for controlling the meter device 24 connected to the compartment B2 for conveying material from its second outlet 40 to zone 3 and to a meter control assembly 280 (C2-3A) for controlling the meter device 24 connected to the compartment C2 for conveying material from its second outlet 40 to zone 3. Similarly, a separate one of the cables 279 can be used to connect the main control module 270 to a meter control assembly 280 (B2-11A) for controlling the meter device 24 connected to the compartment B2 for conveying material from its second outlet 40 to zone 11 and to a meter control assembly 280 (C2-11A) for controlling the meter device 24 connected to the compartment C2 for conveying material from its second outlet 40 to zone 11. 
     Each one of the meter control assemblies 280 includes part of a rotor motor control circuit 282, part of a gate motor control circuit 284 and part of a flow sensor control circuit 286. The other parts of the rotor motor control circuits 282, the gate motor control circuits 284, the flow sensor control circuits 286 and the liquid herbicide solenoid circuits 277 are in the main control module 270 and the operator controls 274. 
     FIG. 19 is another electrical block diagram of the main control module 270 and the operator controls 274 of FIG. 18. The main control module 270 includes a computer 290 interactively connected through an interface unit 292 by lines 294 to the gate motor control circuits 284, the flow sensor control circuits 286, the rotor motor control circuits 282 and the liquid pesticide solenoid circuits 277. The computer can be any device that performs the functions described herein, such as part number LC4DC, from Opto 22 located at Huntington Beach, California. A suitable interface is an Ex 1 Daughter Board also available from Opto 22. The laptop computer 278, the printer 275 and the operator controls 274 are interactively connected to the computer 290. The power supply 272 comprises a 24 volt DC power supply 296 and a 5 volt DC power supply 298. The 24 volt DC power supply 296 is connected to supply power to the computer 290, the gate motor control circuits 284, the flow sensor control circuits 286, the rotor motor control circuits 282, the liquid pesticide solenoid circuits 277 and the operator controls 274. The 5 volt DC power supply 298 is connected to supply power to the rotor motor control circuits 282 and the operator controls 274. 
     FIG. 20 illustrates detailed preferred embodiments of the gate motor control circuits 284, the flow sensor circuits 286, the rotor motor control circuits 282, and the liquid pesticide solenoid circuits 277 of FIG. 19. 
     Each one of the gate motor control circuits 284 can comprise a first switching circuit 300 and a second switching circuit 302 connected in parallel to the 24 volt power supply 296. The first switching circuit 300 is connected in series with a relay 304. A diode 306 is connected in parallel with the relay 304. The second switching circuit 302 is connected in series with a first relay switch 308, the first switch mechanism 256, and a second relay switch 310. A third relay switch 312, the second switch mechanism 258 and a fourth relay switch 314 are connected in parallel with the first relay switch 308, the first switch mechanism 256, and the second relay switch 310. One lead from the gate motor 248 is connected between the first relay switch 308 and the first switch mechanism 256. The other lead from the gate motor 248 is connected between the third relay switch 312 and the second switch mechanism 258. 
     In operation, when the first switching circuit 300 receives a signal from the computer 290, the first switching circuit 300 activates the relay 304 into closing, for instance, the first and fourth relay switches 308, 314 and opening the second and third relay switches 310, 312 making the current flow one direction through the gate motor 248. When the first switching circuit 300 receives another signal from the computer 290, the first switching circuit 300 causes the relay 304 to close, for instance, the second and third relay switches 310, 312 and to open the first and fourth relay switches 308, 314 making the current flow the opposite direction through the gate motor 248. When the second switching circuit 302 receives a signal from the computer 290, the second switching circuit 302 activates the gate motor 248. When the second switching circuit 302 receives another signal from the computer 290, the second switching circuit 302 deactivates the gate motor 248. 
     Each one of the flow sensor control circuits 286 can comprise one of the flow sensors 42 and a first signal circuit 316 connected in series with the 24 volt power supply 296. The signal circuit 316 is designed such that when material flow is sensed by the flow sensor 42, the signal circuit 316 sends a signal to the computer 290. 
     Each one of the rotor motor control circuits 282 can include a motor controller 318 having a plurality of terminals, such as model number BLS540GK24L from Oriental Motor with offices at Torrance, California. The purpose of the motor controller is to control the rpms of the respective motor. A first one of the motor controller terminals is connected to the positive terminal of the 24 volt power supply 296. A second one of the motor controller terminals is connected to the negative terminal of the 24 volt power supply 296. A digital to analog converter 320 is connected between the negative terminal of the 24 volt power supply 296 and a third terminal of the motor controller 318. A fourth terminal of the motor controller 318 is connected to a third switching circuit 322 which in turn is connected to the 5 volt power supply 298. A resistor 324 is connected between a line 326 connecting the negative terminal of the 24 volt power supply 296 to the digital to analog converter 320 and a line 328 connecting the fourth terminal of the motor controller 318 to the third switching circuit 322. One of the leads of the rotor motor 222 is connected to a fifth terminal of the motor controller 318. The other lead of the rotor motor 222 is connected to ground. 
     In operation, the third switching circuit 322 receives signals from the computer 290 that are proportional to the speed of the vehicle 34. Since the motor controller 318 is connected to the third switching circuit 322, the speed of the rotor motor 222 is proportional to the speed of the vehicle 34. 
     Each of the liquid pesticide solenoid circuits 277 can comprise a fourth switching circuit 330 and a coil 332 of one of the liquid pesticide solenoids connected in series with the 24 volt power supply. A diode 334 can be connected in parallel with the coil 332. In operation, when the fourth switching circuit 330 receives a signal from the computer 290, it activates the coil 332 to either open or close the solenoid valve 156. 
     FIG. 21 illustrates a detailed preferred embodiment of the operator controls 274. For each one of the granular material nozzles N 1  -N 13 , the operator controls 274 includes a light source 336 and a fifth switching circuit 338 connected in series with the 24 volt power supply 296. When the flow sensors 42 sense material flow in the material flow paths supplying material to one of the nozzles, e.g., N 1 , the first signal circuits 316 send signals to the computer 290 which sends a signal to the fifth switching circuit 338 which turns on the corresponding light source 336. 
     For each one of the granular material nozzles N 1  -N 13 , the operator controls 274 includes a manual switch 340 and a second signal circuit 342 connected in series with the 24 volt power supply 296. When one of the switches 340 is closed such as the switch 340 corresponding to nozzle N 1 , the corresponding second signal circuit 342 sends a signal to the computer 290 which sends signals to activate the third switching circuits 322 for energizing the metering devices 24 in the material flow paths that supply material to the nozzle N 1 . The operator controls 274 may also include programmable switches which operate like the manual switches 340, but one of the programmable switches can be programmed to turn on and off material flow to a plurality of the zones. 
     The operator controls 274 may house a sixth switching circuit 344 and a third signal circuit 346 connected in series with the 24 volt power supply 296. Alternatively, this circuit can be housed elsewhere, such as in the main control module 270. The speedometer sensor 276 is connected to the sixth switching circuit 344 and provides signals proportional to the speed of the vehicle 34 through the fifth switching circuit 344 and the third signal circuit 346 to the computer 290. The computer 290 adjusts its signals to the third switching circuits 322 to be proportional to the signal the computer 290 receives from the third signal circuit 346. This controls the speed of the rotor motors 222 based on the speed of the vehicle 34. 
     The operator controls 274 further include switches 348 for activating the solenoid valves 156 turning on and off the flow of liquid pesticide and switches for controlling solenoid valves 74, 128, 130 and 142. The switches and circuits for controlling the solenoid valves 74, 128, 130 and 142 can be similar to solenoid valves 74, 128, 130 and 142 that described above in relation to the switches 340. Alternatively, the switches for turning the solenoid valves 74, 128 and 130 on and off can be simply in series with a power source, such as the 24 volt power source, and the coil of the respective solenoid. In other words, these circuits do not have to go through the computer 290. Further, the solenoid valves 142 can be electrically connected to the (Raven) flow control unit referred to in reference to FIG. 11. 
     The switching circuits 300, 302, 322, 330, 338, and 344 can be any circuit(s) as long as it or they perform the functions described above. One such switching circuit is available under model number ODC5Q or OCD5 from Opto 22 located at Huntington Beach, California. Similarly, the signal circuits 316, 342 and 346 can be any circuit(s) as long as it or they perform the functions described above. One such signal circuit is available under model number IDC5Q or IDC5 from Opto 22. 
     In operation, the above described material applying portion of the system 20 performs a method of applying at least one granular material onto a plurality of substantially different zones, comprising the steps of: metering the material(s) from outlets of compartments of a hopper to sections of a collection trough; and conveying and dispensing the materials from outlets of the collection trough through points of release onto the plurality of substantially different zones, such that the material(s) are applied to the zones substantially without pulsing or attrition. Preferably, larger or heavier granules of the material(s) are applied to the zones farther from the points of release, i.e., the outlet ends of the nozzles, than granules applied to the zones closer to the points of release. 
     The present invention can be implemented in a variety of hardware and software configurations as will be apparent to those skilled in the art. An illustrative software embodiment for operating the aforesaid system 20 is included in an Appendix to this specification. The software program is written in the Forth language and appears immediately before the claims. 
     The aforedescribed system 20 allows for substantially uniform and simultaneous application of 12 or more different materials in dry granular form at a wide variety of low application rates including less than 10 pounds per acre (11.2 Kg/ha) to as low as about one ounce per acre (70 gr/ha). The system 20 can apply any material, including pesticides, that fits in the indentations 192 of the rotors 190. Furthermore, the granular material applying portion of the system is 
     boomless and covers swaths of ground up to about 100 feet (30.48 meters) wide. The material being applied to each zone is independently controllable. More specifically, the metering means 24 are individually controllable for each of the zones, such that the system 20 is adapted to simultaneously apply different rates or amounts of the material(s) per unit area to different zones. The metering means 24 are adapted to meter at rates as low as about 2 grams per minute substantially without pulsing or attrition. The system 20 is operable while the vehicle travels at varying speeds in the range of about 3 through 50 miles (4.8 through 80.5 Km) per hour. 
     Those skilled in the art, having the benefit of the teachings of the present invention as hereinabove set forth, can effect numerous modifications thereto. These modifications are to be construed as being encompassed within the scope of the present invention as set forth in the appended claims. ##SPC1##